KR920001983Y1 - Electron gun of color crt - Google Patents

Abstract

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Description

Electron gun for color cathode ray tube

1 is a cross-sectional view of a conventional electron gun having a composite main lens by multiple electric fields.

2 is a front view of a conventional main lens electrode, taken along line A-A in FIG.

3 is a perspective view of a main lens electrode (main focus electrode or final acceleration electrode) according to the present invention.

FIG. 4A is a front view of the electrode shown in FIG. 3, (b) is a sectional view taken along line B-B in (a).

FIG. 5 is an optical equivalent diagram showing the connection state of the electron beam by the electrode shown in FIG.

6 is an optical equivalent diagram showing a state of electron beam connection by a conventional electrode.

* Explanation of symbols for main parts of the drawings

MG, G3, G4: Electrode of main lens P: Beam passing plane of electrode

HR, HG, HB: Beam through hole CH, P: Recessed part

The present invention relates to an electron gun for a color cathode ray tube, the structure of which is improved to improve the image quality by improving the astigmatism in the periphery of the screen.

In general, in order to prevent deterioration of image quality due to astigmatism in the periphery of the screen, the beam is intentionally distorted in the electron gun to reach the screen. An electron beam that passes through the vertical and horizontal slots is formed mainly in the focus lens system. This vertical and horizontal direction is to receive different divergence and focusing power. In order to improve spherical aberration in the main lens system, as shown in FIGS. 1 and 2, the R, G, and B of the beam passing plane P of the main focus electrode G3 and the final acceleration electrode G4, A horizontally recessed indentation portion H through which the beam passes through is formed, and a beam passing hole HR, HG, and HB through which the R, G, and B beams pass independently are formed on the bottom surface thereof. This is to form a multi-field in order to enjoy the same effect that the low magnification of the main lens is a plurality of superimposed, which is a great effect in reducing the spherical aberration. The spherical aberration improving means and the astigmatism improving means both use a certain shape of asymmetric electric field formed around the beam hole and the hole, and of course, the manufacturing process is difficult because the structure of the electrode must be changed. That is, it is very difficult to fabricate the electrodes constituting the entire electron gun because the vertical focusing slots are formed at the prefocus stage, the horizontal recesses and the independent beam passing holes are formed at the main focusing stage, respectively.

The present invention aims to provide an electron gun for a color cathode ray tube that can correct spherical aberration of astigmatism in the main lens system, thereby improving image quality of the cathode ray tube and facilitating its fabrication.

In order to achieve the above object, the present invention forms a stepped recess in the transverse direction on the beam passing plane of the electrode of the main lens system in which the R, G, and B electron beams are finally accelerated and controlled, so that the central portions of the electron beam passing holes are multistage. It is characterized by the fact that it can be dug.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 3, the electrode MG (main focus electrode and final accelerating electrode) of the main lens system has a beam passing hole HR (HG) HB through which a signal signal of red green and blue passes. P) is formed in a straight line at an equal interval on P), and a stepped recess H which crosses the center of these three beam passing holes HR, HG, and HB is formed to a certain depth. Therefore, as shown in FIG. 4, a stepped beam through hole is formed by interposing a portion between the beam through holes and an outer portion of the outer beam through hole in a predetermined depth. Such an electrode is applicable to the main focus electrode and the final acceleration electrode of the electron gun, and may be selectively adopted on one side or both sides.

Looking at the control state of the electron beam in the electron gun having such an electrode, as shown in FIG. That is, the astigmatism of the shape as shown in FIG. 6 caused by the electron gun with the conventional beam passing hole is corrected in the form as shown in FIG. That is, the focusing force on the beam incident to the outer portion of the electron lens is weakened step by step to focus all beam speeds at one point. In other words, when the beam passes through the beam passing hole, the multi-stage focusing area (I), (II) and (III) is formed by the edge of the through hole which is stepped in the longitudinal direction. As it progresses, the focusing force is weakly formed step by step. Therefore, astigmatism due to abnormal refractive index in the outer portion of the electron lens is improved.

The present invention is designed such that the role of the longitudinal and horizontal slots provided in the prefocus stage of the conventional electron gun and the main electrode of the type as shown in FIG. 1 is performed. The correction of astigmatism as well as a multi-field The effect of correcting the spherical aberration can be expected. In particular, since the astigmatism is configured to be corrected by the main lens system, the conventional longitudinal and horizontal slots as described above are not necessary. Therefore, the manufacturing process is easy and the manufacturing cost is also low.

Claims (1)

In an electron gun for a cathodic cathode tube having a cathode and a plurality of electrodes, an electron radiation source, a main focus electrode or final acceleration, which is an electrode of a main lens system in which R, G, and B beam passing holes (HR) (HG) (HB) are formed. An electron gun for a color cathode ray tube, characterized in that a stepped recess (CH) traversing the center of the beam passing holes (HR) (HG) and (HB) is formed in a transverse direction on the beam passing plane (P) of an electrode.